View Full Version : A simple oil change gone South

07-31-2012, 11:53 AM
A week ago, Monday, I went to start an oil change/tune-up. It was time.
Step 1: Get a new set of plugs.
Step 2: Put the front end up on ramps and loosen the oil drain plug.

I have, on Randall's advice, installed the hex-socket-head magnetic drain plugs from McMaster-Carr. On my first attempt to loosen the plug, I felt the wrench twist out. Using more care and more leverage, I succeeded only in reaming out the head of the plug more. Working under ramps wasn't getting me anywhere, so I drove the car up to Good Carma. (As you can tell from the cutesy name, mostly a VW specialist.) Good guys, and I know them well enough to ask them to put the car up on a lift and see if they would be wily and well-equipped enough to get that plug out. Failure! That plug was in there to stay. So I went home & threw just enough oil in it to get me through the week.

Fast forward to last Sunday.

The plan: Remove the sump -- drill out the plug -- clean everything out, replace the plug & put it all back together.

The reality:

Worried that the sump would "fall off" and spill it's contents, I put a jack stand under it. No need for <span style="font-style: italic">THAT!</span> After removing all the bolts, it took me another 30 - 40 minutes with a hammer, a putty knife and a couple of screwdrivers to cut/pry the sump off the bottom of the crankcase. This would have been a drag, had the engine been out of the car. But, working underneath made it a <span style="font-style: italic">real</span> drag.

OK. Sump out -- off to my shop to remove the plug. In brief, the ceramic magnet used on the plug is un-drillable with conventional bits. So, after the drill stopped, I took a punch and whacked the magnet off, then, continued drilling. When I had a 1/2" hole through, I got out my jig-saw to cut <span style="font-style: italic">almost</span> to the threads so I could break it up and pull out the pieces. On my third cut, my back decided that now was the time to seize-up. That's when I cut well through the plug, into the oil pan.

So, I got some JB Weld and put it in the saw kerf, waxed the new plug and ran it in to form threads in the epoxy patch. (So far, so good on this remedy. Time will tell -- but it ought to work.) That done, I spent another 30 - 40 minutes scraping the remains of gasket and Wellseal from the rim of the pan. Enough for one day.

Yesterday (Monday):

Went back to the shop.
1) Cleaned the unholy mess out of the inside of the pan
2) Used a hammer and various aids to ensure that the rim of the pan was straight enough. The previous day's prying had, in fact, distorted it a bit.
3) Took a stock style drain plug and glued a fine, strong, little round magnet to the end.
4) Brought everything home to the garage.

Once home, I threw the remaining Wellseal into the garbage. I am a confirmed Hylomar man now! It comes apart when you need it to.

5) Wrap a rag around the oil pump and pickup screen.
6) 30 - 40 minutes of scraping gasket/Wellseal from the bottom of the crankcase -- <span style="font-style: italic">lots</span> of which fell on my face...

Once the crankcase was ready, the reinstallation of the oil pan, Hylomar and new gasket went unremarkably and <span style="font-style: italic">FINALLY</span> I was ready to install new oil, filter and proceed to the tune up -- which also proceeded unremarkably.


1) <span style="font-style: italic">DON'T</span> over-tighten those pipe-thread fill/drain plugs. I have no-one to blame for this but myself. I installed that plug...

2) I think I am done with socket-head pipe-thread plugs. Say what you will about the square-head plugs, there are many sound methods of removal still available when the head rounds-off. Not nearly as many when one buggers the recess in a socket-head plug.

3) Teflon paste on the threads! (Of course!) (Hindsight is 20-20.)

4) Wellseal seals well, as the name implys. However, it also <span style="font-style: italic">WELDS</span> parts together that, ideally, should remain reasonably un-installable. Hylomar has been mentioned here before. One more +1 on Hylomar which seals just as well but, is <span style="font-style: italic">MUCH</span> more easily disassembled when the need arises. In short: Costs more. Worth it!

Geo Hahn
07-31-2012, 12:16 PM
Mercy! That was starting to sound like that story itemizing the cost of heating your home with wood.

At least you know how to prevent this from recurring.

I use RTV on the oil pan gasket (pressed against a sheet of glass to set) then Hylomar on the gasket to block surface... not much fun scraping while lying under the car.

07-31-2012, 12:41 PM
I agree with the square head sump plug. Pipe plugs just seem to get tighter then you remember putting them in. Worst comes to worse, even with a totally rounded plug, a pipe wrench will get the sucker out.

I glued the pan gasket onto the sump, but then smeared grease on the gasket face that mates to the block. I do this with 90% of my gaskets.

07-31-2012, 01:20 PM

I think Randall's idea of using a hex-socket head drain plug makes a lot of sense, but so does using the square head sump plug. I use the square head plug.

Obviously, one of the problems with either plug is the possibility of reaming out one plug or rounding off the other. The problem, in my opinion, is trying to tighten either one to stop leakage from the plug.

I have found, and have been told by mechanics, that you are unlikely to stop a leak by overly tightening the plug, especially the square head plug. It is just a standard pipe plug and isn't perfectly designed to stop oil from dripping down along the threads. Over-tightening the plug can cause a number of problems, without solving the leaking problem.

So, my advice -- from experience -- is not to overdo the tightening. Instead, put a little non-hardening gasket sealant on the plug while it and the hole are relatively dry or use a little oil-resistant teflon tape (designed for use on engines and available in auto stores). With that approach, you have a better chance of preventing leaks (although not necessarily entirely) and getting the plug out the next time you want to change your oil.

And since you don't have to man-handle the square plug to get it really tight, you can use that special little wrench sold specifically for tightening the square-headed plug. You can't get much leverage using it, but you don't really need such leverage.. And the good thing is that using it prevents rounding the square plug.

I'm sure not everyone will agree with what I have said, but -- hey -- it works for me.

07-31-2012, 01:39 PM
Well, I'm sure sorry you had trouble, Moseso. All I can say is that I've been using hex socket plugs for a long time (combined with teflon paste) and never had any trouble with either removing them or leaks. BTW, a carbide spade drill will go right through a ceramic magnet.

Tapered pipe threads are supposed to deform slightly in order to make the seal, but you should never have to over-tighten them. Sometimes it is necessary to clean up the mating threads a bit (with a suitable tap).

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]It is just a standard pipe plug and isn't perfectly designed to stop oil from dripping down along the threads.[/QUOTE]
Sorry, Ed, but that is just silly. "Standard pipe threads" are absolutely designed to seal perfectly, as they are frequently used inside houses and so on. The plugs I use are only rated to 150 psi, but they are available for much higher pressures (and intended to be leak-free at the rated pressure). An oil drain plug is under less than 1 psi of pressure so it should seal much easier than even normal water piping (which typically carries 50-100 psi).

07-31-2012, 03:40 PM
No need for "sorry," Randall. As I said, I have only myself to blame for 1) probably over-tightening the thing in the first place, and 2) probably being somewhat careless on my first yank trying to get it out.

One of the problems with a socket head screw is its propensity to collect detritus in the socket, thus preventing a good, solid insertion of the wrench. One is well advised to clean the socket before insertion of the wrench when (as in this case) the screw is used in a dirty location. I didn't. My bad.

I'm just continuing my run of Cautionary Tales of Triumphdom. "If this happens to you, don't say I didn't try to warn ya!"


07-31-2012, 04:38 PM

Thanks for setting me straight about these oil drain plugs.

With the plugs I have (from Moss and TRF), attempts to stop slow leaks by continuing to tighten them doesn't seem to work for me; thus the use of oil-resistant Teflon tape and/or a little sealant.

08-01-2012, 02:31 PM
My only comment is about gasket sealers, when I pulled the oil pan off my TR6 several years ago to check the thrust bearing, the Previous owner had put so much Red RTV on the gasket that it ooozed out and was in the sump and even some was in the screen of the oil pump. Its been completely rebuild as of last year and no RTV on my new engine


Geo Hahn
08-01-2012, 03:55 PM
Over use of RTV is a pain for the next guy and potentially problematic. I only use it when I can see the result and will be able to remove next time with the part on the work bench (e.g. timing chain cover, oil pan). Even then I use it minimally (no noodles) and on one side of the gasket only.

08-01-2012, 04:49 PM
Hylomar and Wellseal are Rolls-Royce designed gasket goo for World War 2!

Both are useless compared the to the best modern of which my favourite is Loctite 5699 or Loctite Grey as it is sometimes known. It'll seal anything, the joint is easily broken and it's easy to clean off when you rebuild.

I stopped using Hylomar and Wellseal at least twenty years ago and am just rebuilding my TR3A engine with 5699 now.


Geo Hahn
08-01-2012, 05:20 PM
I've never really understood the (possibly subtle) differences in their various RTVs. I have generally used the 'copper' which seems similar to the 'grey':

Grey vs Copper (https://www.etrailer.com/comparison.aspx?pc=LT37464&amp;pc2=LT37466)

But if it is something I expect to take apart one day (and that includes almost everything) I still like Hylomar on at least one side of the gasket.

08-01-2012, 05:33 PM
No question about it.... Overuse of gasket maker or sealant is not a good idea, especially on the sump gasket.

My reference to sealant, however, referred to putting just a little on the threads of the sump plug to stop or reduce leakage rather than trying to stop a leak by over-tightening the plug. Or, one could use oil-resistant Teflon tape.

I've seen these plugs tightened so tight that a long-handled wrench was needed to get them out!

08-01-2012, 09:46 PM
I'm sure I am over-cautious, but I always worry about small pieces of Teflon tape accumulating on the oil pump pick-up screen.


08-02-2012, 07:55 AM

Your caution is justified. So, if you put Teflon tape on a sump plug or on a transmission drain plug, use only a very small amount. As the plug is screwed in, you'll notice that the Teflon tape is pushed up toward the head of the plug. It seems to "seal" at the top end of the plug more than at the bottom end of the plug. So, the possibility of pieces of tape breaking loose and flowing into the sump is probably small.

However, when you take the plug out, it is possible that small pieces of tape may remain in the hole, and these should be removed with a brush so that when you replace the plug you don't push them up into the sump.

If Teflon tape is a worry, then use a little (just a little) gasket sealant on the plug threads. Same holds true when you remove the plug for an oil change: be sure to clean the threads for any old sealant left clinging to the threads.

Now... all of this is useful only if you find that your plugs are leaking. Chances are, even without over-tightening the plugs, that they won't leak. In that case, you'll want to use a little (a little) antiseize lubricant on them. (BTW - antiseize lubricant can also cut down on leaks.)

But if a little leak is no great problem, for you... then let 'er drip. As has often been said, this oil on the undercarriage helps prevent rust.

BTW: Overtightening a plug can result in stripping or rounding off the square head.... but it can also -- if tightened sufficiently -- do damage to the casing around the hole, especially if the casing is made of aluminum. A crack caused by overtightening a plug there can be a big problem.

08-02-2012, 08:14 AM
Or you could just use the paste. Totally impossible for it to form strings to clog small passages, and you don't have to worry about getting each and every joint "just right". And it doubles as anti-seize for relatively low temperature joints (like an oil drain).

The "professionals" who changed the water pump on my Buick a few years back used RTV. It wound up in the shop several times before we finally figured out that the strings of RTV had literally clogged the passage to the heater core! (It has an orifice to limit how much pressure the heater core sees from the water pump, according to the manual. Had to clean it and change the coolant twice before all the gunk was gone.)

Yup, Hylomar is "old school". But Rolls Royce was justly proud of being able to park their cars over a white sheet and not soil it. That would be good enough for me!

Oh, and just to restate the obvious : Many times the drain plug is blamed for leaks that actually happen higher up. The plug is at the lowest point, so naturally any leak will drip from there, even when the film to the leak is not visible.

08-02-2012, 08:12 PM

Absolutely right... many times the leaks happen higher up and flow down to the plug. Always a good idea to check that before fussing with the drain plug.

08-03-2012, 11:56 AM

But if a little leak is no great problem, for you... then let 'er drip. As has often been said, this oil on the undercarriage helps prevent rust.

Now your talking...I've always believed old cars are supposed to leak (except the battery)! If they don't, I have to spray oil onto my rag when I'm wiping it down anyway...a little drip just makes it that much easier.